So I have a 68 350 bird. Got it from relative back when I was in High school in the 80’s. Always told it had a different engine. Last year lost 2nd gear in the tranny. Had to pull the motor and tranny out the front to get it out. Engine is a 481990 casting which looks to be a 71 or 72 350 block. Heads have ‘A 94’ on them. Engine needs serious cleaning, gaskets, etc., but ran fine. Is it worth it to put new heads on, cam, intake, 4 bbl on and upgrade the tranny? Not sure where the money is best spent since it doesn’t appear to be numbers matching. I’m mechanically inclined, but not a mechanic. Appreciate all opinions.